Particle sizes can be measured using a variety of techniques depending on the size and nature of the material:
|Technique||Dynamic light scattering||Laser diffraction||Particle tracking||Disc centrifuge|
|Approximate suitable particle size||< 1 µm||> 1 µm||< 1 µm||< 10 µm|
Fast measurementZeta potential
Dry powdersLiquid dispersions
Good for multi-modal systemsAqueous dispersions
Higher resolutionLonger preparation time
How does it work?
Dynamic light scattering is also known as photon correlation spectroscopy, and measures the way photon scattering changes with time, which is a function of the size of the particles (the hydrodynamic diameter). Laser diffraction is an angular technique, in which the angle and intensity of the scattering are used to determine the particle size.
Particle tracking uses a laser beam shone through a sample in a dispersant, and the scattering particles moving under Brownian motion are tracked by software which measures how fast they are moving. This is used to calculate the size of the particles.
In the disc centrifuge, a dispersed sample is spun at very high speeds in a gradient solution. The time that the particles take to settle out is related to their size.
Suspensions and emulsions; dry powders; food industry; pharmaceuticals; microcapsules; fine chemicals; polymers; pesticides; water analysis; flocculation; membrane filtration; cosmetics; perfumes; creams; petrochemicals; fuels; pigments; inks; toners; paints; varnishes.
Sample handling requirements:
Powders or dispersions.
Dr Ian Hancox, 024 76 150380 email i dot hancox at warwick dot ac dot uk
|Warwick collect/analyse data|
|Warwick collect data|
|Available to user with expertise/ contribution|
|Spare capacity for collaborative research|